Application of ROMS for the Spencer Gulf and on the adjacent shelf of South Australia
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Transcript of Application of ROMS for the Spencer Gulf and on the adjacent shelf of South Australia
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Application of ROMS for the Spencer Gulf
and on the adjacent shelf of South Australia
Carlos Teixeira & SARDI Oceanography Group
Aquatic Sciences
2009 ROMS/TOMS Asia-Pacific Workshop
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Wintertime Outflow of Wintertime Outflow of Spencer GulfSpencer Gulf
Contours of near-bottom salinity (16-23 June 1986. Lennon et al. 1987)
During winter, the gulf waters are cooled and become denser than the shelf waters. This dense water flows out to the adjacent shelf.
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Sea Surface Temperature from satellite measurements
Summertime OutflowSummertime Outflow
During summer, the gulf waters become denser due the evaporation, but the upwelled waters in the shelf block the gulf outflow.
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SAIMOS
• To monitor and better understand the gulfs and shelf circulation, $6.5M invested in the Southern Australian Integrated Marine Observing System.
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Planned Planned SAIMOS SAIMOS Infrastructure:Infrastructure:
Shelf/Slope Moorings
Reference Station
• Monthly CTD Stations for 2 years
HF Radar
PLUS
• Gliders
The data will be used to initialize, force and validate the hydrodynamic/bio-geochemical model for the region.
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What modelling we intend to do?
• Idealized forcing to better understand the fundamental physics of the circulation within the Spencer Gulf (my PhD thesis)
• Hydrodynamic/ Biogeochemical model for the Spencer Gulf and adjacent shelf
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Tides
• Barotropic Experiment
• OTPS / TP07.1 tidal forcing
• Free surface CHAPMAN BC
• 2D Momentum FLATHER BC
• Bottom Friction:– Linear– Quadratic– Logarithmic
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Grid and Validation
Spencer Gulf
San Vincent
Gulf
• 3 x 3 Km grid• Amplitudes and Phases compared with Australian National Tide Tables
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Amplitudes M2
West Coast
East Coast
San Vincent GulfSpencer Gulf
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Phases M2
West Coast
East Coast
San Vincent GulfSpencer Gulf
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Summary:• Best results with Quadratic Law scheme for Bottom friction. • Good agreement with ANTT in the stations outside the gulfs• Reasonable inside the Spencer Gulf • Poor inside San Vincente Gulf
Next Steps:• Nested model for gulfs using a high resolution grid
• Assimilation of SSH data inside the gulfs?
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Local vs Remote wind?
Remote Wind =
Coastal Trapped Waves
Local
Wind
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• 5 x 5 Km uniform grid• 20 Sigma levels • Analytical initial values for temperature and salinity
Same vertical profile everywhere (no horizontal gradient).
• Free surface CHAPMAN BC• 2D Momentum FLATHER BC• Gradient BC for 3D momentum and tracers• Tangent RADIATION_2D and Sponge area used in
the eastern boundary• Mellor and Yamada 2.5 turbulence closure method • 3rd-order upstream horizontal advection• 4th-order centered vertical advection
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Remote wind
– Mode 1 CTW cross-shelf eigenfunction determined for the western boundary topography (Brink and Chapman,1985).
– Eigenfunction used to create SSH and external
velocities in the western boundary (Paddle).
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Remote Wind – CTWResults
Paddle
Sea Level
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Paddle
External Velocity
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Local wind– 10 days oscillatory zonal and meridional
wind Stress (0.1 Pa)– Wind Stress tapered to the gulfs area
17.5 Days
Wind Stress
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Local Wind – Cross ShoreResults
Sea Level
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1
2
3
External Velocity
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Diagnostics
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4
7
9
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COADS Wind Forcing
• Model forced with COADS monthly winds for 1 year;
• Passive Tracers used to study the connection between the Gulfs;
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Summary from Wind Model• ROMS model with analytical initial conditions and
forcing was very valuable to better understand the circulation within Spencer Gulf
• Remote winds will be unimportant to the circulation within the gulfs;
• Local winds will generate a weak circulation in most
part of the gulf, with the exception of shallow areas;
• There is a strong transport from the SG to the SVG,
but not from SVG to the SG.
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Next Steps….
• Use Met Stations and local atmospheric model data for better represent the wind stress inside the Gulfs and compare the results with SAIMOS data;
Summer Scenario:
• Initiate the model with realistic data and atmospheric forcing to try to reproduce summer scenario.
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Thank you!